| Autor: |
Pollenz, Richard S., Sullivan, Hillary R., Holmes, Jennifer, Necela, Brian, Peterson, Richard E. |
| Zdroj: |
Journal of Biological Chemistry; November 1996, Vol. 271 Issue: 48 p30886-30896, 11p |
| Abstrakt: |
cDNAs encoding two distinct basic helix-loop-helix/PER-ARNT-SIM (bHLH/PAS) proteins with similarity to the mammalian aryl hydrocarbon nuclear translocator (ARNT) protein were isolated from RTG-2 rainbow trout gonad cells. The deduced proteins, termed rtARNTaand rtARNTb, are identical over the first 533 amino acids and contain a basic helix-loop-helix domain that is 100% identical to human ARNT. rtARNTaand rtARNTbdiffer in their COOH-terminal domains due to the presence of an additional 373 base pairs of sequence that have the characteristics of an alternatively spliced exon. The presence of the 373-base pair region causes a shift in the reading frame. rtARNTalacks the sequence and has a COOH-terminal domain of 104 residues rich in proline, serine, and threonine. rtARNTbcontains the sequence and has a COOH-terminal domain of 190 residues rich in glutamine and asparagine. mRNAs for both rtARNT splice variants were detected in RTG-2 gonad cells, trout liver, and gonad tissue. rtARNTaand rtARNbprotein were identified in cell lysates from RTG-2 cells. Transfection of rtARNT expression vectors into murine Hepa-1 cells that are defective in ARNT function (type II) result in rtARNT protein expression localized to the nucleus. Treatment of these cells with 2,3,7,8-tetrachlorodibenzo-p-dioxin results in a 20-fold greater induction of endogenous P4501A1 protein in cells expressing rtARNTbwhen compared with rtARNTa, even though both proteins effectively dimerize with the aryl hydrocarbon receptor. The decreased function of rtARNTaappears to be due to inefficient binding of rtARNTa·;AHR complexes to DNA. In addition, the presence of rtARNTacan reduce the aryl hydrocarbon receptor-dependent function of rtARNTbin vivoand in vitro. |
| Databáze: |
Supplemental Index |
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